SpringMVC文件上传及拦截器

梦里梦外; 2023-10-06 05:59 1阅读 0赞

#### SpringMVC文件上传及拦截器 ####

*  文件上传
 *  拦截器

## 文件上传 ##

思路：

和Servlet方式的本质一样，都是通过commons-fileupload.jar和
    commons-io.jar。
    SpringMVC可以简化文件上传的代码，但是必须满足条件：
    实现MultipartResolver接口 ；
    而该接口的实现类SpringMVC也已经提供了CommonsMultipartResolver

具体步骤：（直接使用CommonsMultipartResolver实现上传）  
a.jar包  
commons-fileupload.jar、commons-io.jar  
b.配置CommonsMultipartResolver

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    	<property name="defaultEncoding" value="UTF-8"></property>
    	
    	<property name="maxUploadSize" value="104857600"></property>
    </bean>

**id必须为multipartResolver  
因为IOC容器在初始化时，会自动寻找一个id=multipartResolver的bean，并将其添加到IOC容器中，如果  
没有发现该ID则会略过**

前端：

**注意：  
表单的method一定要是post，并且要有enctype="multipart/form-data"该属性，如果模式不是post会报500**

控制器：

@RequestMapping(value = "testUpload",method = RequestMethod.POST)
    		public String testUpload(@RequestParam("desc") String desc,@RequestParam("file") MultipartFile file) throws IOException {
        
    			System.out.println("文件描述"+desc);
    			//jsp中上传的文件：file。
    			InputStream inputStream = file.getInputStream();
    			String Oname = file.getOriginalFilename();//文件原始的名字
    			//将文件上传到服务器的某个硬盘文件中
    			OutputStream out=new FileOutputStream("d:\\"+Oname);
    			
    			byte[] bs=new byte[1024];
    			int len=-1;
    			while ((len=inputStream.read(bs))!=-1) {
        //文件没读完就不是-1
    				out.write(bs, 0, len);
    				
    			}
    			out.close();
    			inputStream.close();
    			System.out.println(Oname+"上传成功");
    			return "successe";
    		}

## 拦截器 ##

拦截器的原理和过滤器相同。  
SpringMVC：要想实现拦截器，必须实现一个接口HandlerInterceptor  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70]  
步骤：  
a.编写拦截器 实现HandlerInterceptor

package org.cduck.interceptor;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    public class MyInterceptor implements HandlerInterceptor{
        
    
    	@Override
    	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
    			throws Exception {
        
    		System.out.println("渲染（jsp）页面后拦截");
    	}
    
    	@Override
    	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
    			throws Exception {
        
    		System.out.println("拦截响应。。");
    	}
    
    	@Override
    	public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception {
        
    		
    		System.out.println("拦截请求。。。");
    		return true;
    	}
    
    }

b.配置：将自己写的拦截器 配置到springmvc中（spring）

<mvc:interceptors>
    
    <mvc:interceptor>
    
    <mvc:mapping path="/**"/>
    
    <mvc:exclude-mapping path="/testUpload"/>
    
    <bean class="org.cduck.interceptor.MyInterceptor"></bean>
    </mvc:interceptor>
    
    </mvc:interceptors>

实现拦截器链（多个拦截器）：

只需要再写一个拦截器：

package org.cduck.interceptor;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    public class MyInterceptor2 implements HandlerInterceptor{
        
    
    	@Override
    	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
    			throws Exception {
        
    		System.out.println("渲染（jsp）页面后拦截2");
    	}
    
    	@Override
    	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
    			throws Exception {
        
    		System.out.println("22222拦截响应。。");
    	}
    
    	@Override
    	public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception {
        
    		System.out.println("22222222222222拦截请求。。。");
    		return true;
    	}
    
    }

然后再配置一次：

<mvc:interceptors>
    
    <mvc:interceptor>
    
    <mvc:mapping path="/**"/>
    
    <mvc:exclude-mapping path="/testUpload"/>
    
    <bean class="org.cduck.interceptor.MyInterceptor2"></bean>
    </mvc:interceptor>
    
    </mvc:interceptors>

拦截器链的执行顺序：

拦截器1拦截请求- >拦截器2拦截请求 - >请求方法 -> 拦截器2处理响应->
    拦截器1处理响应->   渲染（jsp）页面后拦截2->渲染（jsp）页面后拦截

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200501150820525.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxMDQwNTU5,size_16,color_FFFFFF,t_70